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Best Practices for

Environmental Site Management

Presented to

CLU-InApril 3, 2018

A Practical Guide for Applying

Environmental Sequence Stratigraphy (ESS)

to Improve Conceptual Site Models

US EPA Emphasis on Geologic Based CSMs and Remediation Based Geology

► EPA is committed to applying stratigraphic analysis to our hazardous waste

sites. It is our expectation that stratigraphic analysis utilizing the methods

presented in this new EPA guidance be considered at each site.

► EPA has advocated updating existing conceptual site models when new data

are obtained. This new EPA guidance presents a methodology utilizing

existing data, new data are not necessarily required to perform this analysis.

► Updating existing conceptual site models can occur at any time, from EPA’s

perspective this can occur in the near term.

► Stratigraphic analysis is best conducted by experienced stratigraphers. EPA

will be writing into contracts for conceptual site models developed on our

behalf be prepared in collaboration with a stratigrapher.

► EPA’s expectation is for work products and reports submitted to our agency

also be checked by an knowledgeable and experienced stratigrapher.

► Best Practice series of papers, two completed three in prep

► BEST PRACTICES FOR ENVIRONMENTAL SITE MANAGEMENT,

A Practical Guide for Applying Environmental Sequence Stratigraphy to

Improve Conceptual Site Models


Contents of a Groundwater Monitoring Report

► BEST PRACTICES FOR ENVIRONMENTAL SITE MANAGEMENT, A

Framework for Characterizing Groundwater/Surface Water Interaction


Geology Characterization of Hazardous Waste Sites


Groundwater Sampling Methods

► Stay tuned, publication and training announcements will be made in

EPA’s TechDirect

US EPA Geology Initiative

General Benefits of ESS Approach

► Identify groundwater flow paths and preferential

contaminant migration pathways

► Map and predict contaminant mass transport (high

permeability) zones and matrix diffusion-related storage

(low permeability) zones

► Identify data gaps and determine a focused HRSC program,

if needed

► Optimize groundwater monitoring program

► Improve efficiency and timeliness of remediating

contaminated groundwater

► Reduce cost of remediation

US EPA Geology Initiative

► 90% of mass flux contaminant transport at Superfund

sites has been shown to be through 10% of aquifer

material.

► A site conceptual model that accurately reflects the

geologic plumbing is essential for remedy selection

and implementation.

► Site conceptual models that do not consider

depositional environment tend to incorrectly interpret

the geologic plumbing which leads to faulty remedy

selection/design and unnecessarily lengthy cleanups.

Focus on Depositional Environments

Stratigraphic “Rules of Thumb”

Case Studies

► Paradigm Shift Remediation Geology

► Why Environmental Sequence Stratigraphy (ESS)

(The Challenge of Subsurface Heterogeneity)

► What is ESS?

► Case Studies

► Silicon Valley groundwater remediation project

► Kirtland AFB, Albuquerque NM

Presentation Outline

Paradigm Shift Remediation Geology

The science that deals with the earth's physical

structure and substance, its history, and the

processes that act on it.

Geology (stratigraphy) defines the subsurface

“plumbing” that is the primary control of groundwater

flow and contaminant transport.

A Definition of Geology

Just like there are specialties in the field of medicine…

MD

general practice anesthesiology cardiology

gastroenterology

OB/GYN

dermatology psychiatry

neurology

seismologypediatrics urologyoncology podiatry

radiology ophthalmology pathology

orthopedic

hematology

Stratigraphy, Subset of Geology: Interpretation of stratified rocks

Geology

mineralogy geophysics marine geology

geochemistry

economic geology

structural geology sedimentology

stratigraphy

seismologypaleontology tectonicshydrogeology petroleum geology

engineering geology geomorphology igneous petrology

volcanology

metamorphic petrology

Unified Soil Classification System:

Standard Practice for Classifying Soils(Chart from ASTM)

Traditional Focus on Engineering

Lithostratigraphic Correlations

Connect sands to sands, clays to clays

Lithostratigraphic Correlations

Connect sands to sands, clays to clays

(Zoomed in)

Groundwater Production IndustryTraditional Approach to the Subsurface

Water supply studies based on assumptions of homogeneousand isotropic conditions, steady-state observations

State of the practice is to apply Darcy’s law,

assume homogeneous and isotropic conditions witin

layers of interestContaminant plumeGroundwater gradient

Traditional Focus on Hydrology

Why

Environmental Sequence Stratigraphy

(ESS)?

The Challenge of Subsurface Heterogeneity

► Outcrop analog of meandering fluvial deposits (Upper Cretaceous Horseshoe Canyon Formation, Alberta, Canada)

The Problem of IgnoringAquifer Heterogeneity

The Problem ofAquifer Heterogeneity

250 m

10

m

(Image Zoomed In)

Gray = channel deposits

(sand/gravel)

Brown = flood plain deposits

(silt/clay)

250 m

10

m


250 m

10

m


250 m

1 23

10

m


Cost Savings Example: Optimize Plume Containment Remedy

125’ extraction

interval

(includes non-

impacted strata)

Remediation System Design (Before ESS)•12 extraction wells

•~200 gpm per well

•1,261 million gallons per year

Total cost = $82 million

After ESS

Estimated Remediation System Cost (After ESS)•13 extraction wells

•46 gpm per well

•314 million gallons per year

Total cost = $26.5 million

35’ extraction

interval

(impacted

strata only)

Before ESS

Cost Savings Example: Optimize Plume Containment Remedy

125’ extraction

interval

(includes non-

impacted strata)

After ESS 35’ extraction

interval

(impacted

strata only)

Before ESS

Significantly reduced quantity of extracted groundwater (by 75%)

Significantly reduced cost of remediation (by >$50 million)

More than 126,000 sites across

the U.S. require remediation

More than 12,000 of these sites

are considered "complex"

“…due to inherent geologic

complexities, restoration within

the next 50-100 years is likely

not achievable.”

Alternatives for Managing the Nation's Complex

Contaminated Groundwater Sites National Academy of Sciences Committee on Future Options for

Management in the Nation's Subsurface Remediation Effort, 2013

Geology/Heterogeneity Matters

What is ESS?

Early days of exploration and

production, once oil reservoir was

discovered, production was limited

by facilities capacity (engineering

focus).

As production declined, geology

became increasingly critical for

economical operations.

Billions of dollars have been invested

in research and development of

stratigraphic controls on fluid flow.

Emergence of Petroleum Geology in the Oil Industry

Determine depositional

environment, which is

the foundation of the

ESS evaluation

0

100

200

300

400

Fining up

Fining up

Fining up

Fining up

Coarsening up

Cyclicity

Depth (Ft - M

SL)

Clay

Gravel

Grain-size increasing

Unconformity

Unconformity

1 2 3

Leverage existing

lithology data: format

to emphasize vertical

grainsize distribution

Map and predict in 3-D

the subsurface conditions

away from

the data points

The Environmental Sequence Stratigraphy (ESS) Process

Alluvial fan facies model Meandering river facies model Coastal depositional systems

Glacial depositional systems

ESS Is About Pattern Recognition


Depositional environments

have distinctive vertical

grain size distributions













Lithology data is not being used to its full capacity

Boring Logs CPT Logs Geophysical Logs

ESS Is the Means to Optimize Existing Data

► “All we have are these lousy

USCS boring logs”

► USCS is not a geologic

description of the lithology

► Different geologists

► Different drilling methods

► Different sampling intervals

► Etc.

Getting More from Existing Site Data

Graphic Grain-Size Logs (GSLs)

► Existing data is formatted for

stratigraphic interpretation

► Reveals the “hidden” stratigraphic

information available with existing

lithology data

How to Find Buried Channelswith Existing Data

This SM interval is a fine to medium-grained silty

sand


This SM interval is a fine- to coarse-grained silty

sand with gravel, representative of a channel

deposit.


1. Reformat existing data to identify sequences, and

2. Apply facies models, stratigraphic “rules of thumb” to correlate and

map the subsurface, predict character of heterogeneity present

Example from GW site in S. CA, USA

500 feet

Permeable streaks commonly at

bases of channel complex


Mapped Buried Sand Channels

Yellow = channel deposits

(sand/gravel)

Gray = flood plain deposits

(silt/clay)

vs

Mapped Buried Sand ChannelsUSCS-Based Cross Section ESS-Based Cross Section

Stratigraphic “Rules of Thumb”

Stratigraphically Defensible Interpretation: “Rules of Thumb”

► Interpretation must consider depositional environment, facies model

► Patterns, not “tops”

► Consider erosional events

► Correlate clays

► Look for paleosols

► Channels have erosive bases, flat tops

► Increasing heterogeneity with clay content in fluvial systems

► Vertical heterogeneity is an indicator of lateral heterogeneity

(fluvial systems)

► Look for Maximum Flooding Surfaces (coastal settings)

► Avoid the “mounded clay”

► Avoid “Pillars”

“Pillar Facies”

The “mounded clay”



Updated CSM

Q&A Break

Case Studies

Former Semiconductor

Manufacturing Site:

VOC groundwater plume

commingled with neighboring

plumes

Scale: Less than 10 acres,

approximately 100 feet depth of

investigation

Geology: Meandering /

anastamosing stream (buried sand

channels)

Lithology Data: Borehole logs

Approach: In response to five-

year review, use ESS to define

contaminant migration pathways

from off-site sources

Case StudySilicon Valley Commingled Plumes

Zone A

Zone B1

Zone B2

Zone B3

Zone B4

Silicon Valley Site: Original CSM

= Off site source area

Original CSM – B1 Zone

Grain Size Trends and Graphic Grain Size Logs

► Normalize different vintages of data collection,

etc.

► Identify trends in maximum grain size

(indicator of energy level in depositional

processes)

► Example of fining upward channel deposit

► Channels migrate laterally over time (point bar

deposits)

► Channel “signature” provides basis for

mapping

Depositional Environment

Boring Log GSL

A’A

HSU 1HSU 2

ON-SITE OFF-SITE

Posting GSLsand Channel Interpretation

HSU 2

Source area

remediation

= Off-site source

area

A A’

A

A’

Best Practice, ESS-Based CSM:Defines Buried Channels

HSU 2 HSU 2

HSU 2HSU 2

Resolve the Mystery of Commingled Plumes

Resolve the Mystery of Commingled Plumes

Increasing concentrations

Focused HRSC Program

HSU2

NORTH

EC log

► MIP/HPT program to validate CSM,

identify additional channel pathways from

off-site source(s)

► Channel deposits (sand and gravel)

validated as contaminant pathways

► Plume “maturity” decreases with depth

ESS-based CSMOriginal CSM

Improved CSM Defines Source of Commingled Plumes

Outcomes and Contribution to EPA

New CSM reduced uncertainty and lead to resolution of a

5 year review issue.

New CSM will provide rationale for monitoring well screen

depth and monitoring objectives.

New CSM will result in clean up by parties responsible for

each site related release.

Kirtland AFB, Albuquerque NMUniting Stakeholders Through Focus on Geology

► Jet fuel LNAPL up-dip, EDB dissolved phase plume in drinking water aquifer downdip

► Regional Scale: Rio Grande Rift

► Plume Scale: ~7,000 X 1,200 ft.

► Water table approx. 500’ bgs, ~1000 ft. borings

► Multiple stakeholders including the public, USGS, NMED, AF, Sandia Nat’l Labs, PBR contractor

► Public relations issues

► Technical team splintering

BFF

Communication Problems

► Air Force and NMED at odds

► Limited exchange of

information

► Ineffective integration of data

► Political and organizational

groups brought public attention

to the leak

► Public perceived that nothing

was being done

Kirtland AFB- Previous Section Example

“If this is simply a sand box, why can’t you give me a final answer?”

Reformulating The Approach► Standup technical working

groups: Reboot Collaboration

► Refocus on the Common Enemy:

– Uncertainty Created by

Subsurface Heterogeneity

► Implement a data-driven decision

process for characterizing,

evaluating and selecting interim

measures under RCRA

► Increase public awareness and

involvement through proactive

and transparent communication

► Giving direct access to technical

experts

ESS Step 1A Depositional Model – The Framework In Which We Understand The Problem

1000 ft

Real World Analogs: Plume in Context of

Braided River

Plume

Permeable

Sediment

1000ft

Real World Analogs: Plume in Context of

Braided River

Plume

ESS Step 2Integrating Data: Geology Anchoring The Technical Team

ESS Step 3Kirtland AFB - ESS Correlation(Regional Scale)

1 mile

Kirtland AFB - ESS Correlation(Plume Scale)

Stratigraphic context

of “450’ clay”

Recognition of

correlateable, dipping

fine-grained beds:

lateral spread of

contaminant plume

Geophysical logs calibrated

to grain size logs confirm GP

logs as valid lithologic

indicators

Understanding Plume Extents and Impacts of Rising Water Table

Public OutreachUsing The CSM to Communicate

Communication Problems – Resolved Through Effective CSM Development

Poster: Borehole Geologic Log

Summary, ESS Benefits

Reduce uncertainty with respect to project end point and time to complete

Identify groundwater flow paths and preferential contaminant migration pathways

Map and predict contaminant mass transport (high permeability) zones and matrix diffusion-related storage (low permeability) zones

Identify data gaps and determine a focused HRSC program, if needed

Optimize groundwater monitoring program

Improve efficiency and timeliness of remediating contaminated groundwater

Reduce cost of remediation

Thank you!

Rick Cramer

[email protected]

Mike Shultz

[email protected]

Colin Plank

[email protected]

Herb Levine

[email protected]

Presented to CLU-In · paleontology seismology hydrogeology petroleum geology tectonics engineering geology geomorphology igneous petrology ... drinking water aquifer downdip

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